1. **State the problem:** Solve the equation $$39 = x - 72$$ for $$x$$. 2. **Formula and rules:** To isolate $$x$$, add 72 to both sides of the equation to cancel out the $$-72$$. 3. **Intermediate work:** $$39 = x - 72$$ Add 72 to both sides: $$39 + 72 = x - 72 + 72$$ $$39 + 72 = x + \cancel{-72} + \cancel{72}$$ 4. **Simplify:** $$111 = x$$ 5. **Final answer:** $$x = 111$$ This means the value of $$x$$ that satisfies the equation is 111.